Web folding apparatus and method

ABSTRACT

A machine for interfolding tissue webs which includes a series of folding devices having successive left and right pairs of curved folding shoulders, with the shoulders in each pair being spaced apart to define a generally slot-shaped opening therebetween. An adjustable conveyor draws the longitudinal edge portions of each web along the respective folding shoulders of the corresponding folding device, and the device holds the received edge portions in spaced-apart relationship with each other until after the web reaches the second succeeding folding device. The second succeeding device then closes the edge portions to fold the web into a continuously moving stack of webs. As each web is received by the corresponding folding device, a shallow trough is formed in the web, and the infeed portion of the device directs this trough at approximately a right angle with respect to the path of the continuously moving stack. The trough is then turned inside out, and the web direction is changed so that it is substantially parallel to the path of the stack. The trough is gradually closed as it moves along the curved folding shoulders of the device and on past the next and then the next device. Before the trough is completely closed, an edge portion of the succeeding web is inserted therein. The webs are led to the folding devices from a plurality of supply rolls disposed along a single side of the machine. One supply roll is provided for each group of four folding devices, and the material from each roll is cut to the appropriate width to form the webs as it is advanced toward the folding devices. The various supply rolls include inflatable core assemblies which may be quickly and easily inserted in and withdrawn from the paperboard cores of the rolls. When the material from a given roll is exhausted, a back-up roll is moved into position, and the spent core is deposited on a conveyor which transports it to one end of the machine.

United States Patent [191 Lee et al.

[ 5] Oct. 15, 1974 WEB FOLDING APPARATUS AND METHOD [73] Assignee: International Paper Company, New

York, NY.

22 Filed: Feb. 12, 1971 21 Appl. No: 114,994

[52] US. Cl. 270/40 [51] int. Cl 13411 1/30 58] Field of Search 270/5, 6, 40, 41

[56] References Cited UNITED STATES PATENTS 2,642,279 6/1953 Teall 270/40 2,868,539 1/1959 Koons et al 270/41 3,147,969 9/1964 Martin 270/52 3,285,599 11/1966 Pherson et al. 270/40 3,291,678 12/1966 Enloe et al 270/40 X 3,401,928 9/1968 Frick 1 270/40 3,635,327 1/1972 Thiessen 198/126 3,682,468 8/1972 Schriber 270/52 Primary Examiner-Robert W. Michell Assistant Examiner-A. J. Heinz Attorney, Agent, or Firm-Charles B. Smith; Robert R. Jackson [5 7 ABSTRACT A machine for interfolding tissue webs which includes a series of folding devices having successive left and right pairs of curved folding shoulders, with the shoulders in each pair being spaced apart to define a generally slot-shaped opening therebetween. An adjustable conveyor draws the longitudinal edge portions of each web along the respective folding shoulders of the corresponding folding device, and the device holds the received edge portions in spaced-apart relationship with each other until after the web reaches the second succeeding folding device. The second succeeding device then closes the edge portions to fold the web into a continuously moving stack of webs.

As each web is received by the corresponding folding device, a shallow trough is formed in the web, and the infeed portion of the device directs this trough at approximately a right angle with respect to the path of the continuously moving stack. The trough is then turned inside out, and the web direction is changed so that it is substantially parallel to the path of the stack. The trough is gradually closed as it moves along the curved folding shoulders of the device and on past the next and then the next device. Before the trough is completely closed, an edge portion of the succeeding web is inserted therein.

The webs are led to the folding devices from a plurality of supply rolls disposed along a single side of the machine. One supply roll is provided for each group of four folding devices, and the material from each roll is cut to the appropriate width to form the webs as it is advanced toward the folding devices. The various supply rolls include inflatable core assemblies which may be quickly and easily inserted in and withdrawn from the paperboard cores of the rolls. When the material from a given roll is exhausted, a back-up roll is moved into position, and the spent core is deposited on a conveyor which transports it to one end of the machine.

17 Claims, 41 Drawing Figures Pmmmum 1 5x914 v 3 520 sum '03 or 14 PATENIED OCT 1 SL974 sum as ur 14 PATEmgunm 1 51914 saw 0s or 14 mm /l sis-341L620 sum :10 ur 14 PATENTEU 1 5 PATENTED um I 51914 sum *1: or 14 PATENTED OCT 1 5 i974 sum 130F111 AWN PATENTED 0m 1 5:374

saw-1a m m BACKGROUND OF THE INVENTION This invention relates to an apparatus and method for interfolding a succession of webs and more particularly to an apparatus and method for advancing the webs along a feed path and interfolding the webs through the use of a series of folding devices positioned along the path.

There has been developed over the years a number of tissue interfolding machines. Representative machines of this type are disclosed, for example, in US. Pat. No. 2,642,279 granted June 15, 1953; US Pat. No. 3,285,599 granted Nov. 15, 1966, US. Pat. No. 3,472,504 granted Oct. 14, 1969, and U.S. Pat. No. 3,542,356, granted Nov. 24, 1970. As will be understood, consumer size boxes of tissue commonly contain 100 or more separate sheets in short lengths cut from a long stack. The stack is assembled by bringing together a corresponding number of tissue webs from separate supply rolls. As the webs are assembled in the stack, they are interfolded by a series of folding devices to produce one or more longitudinal folds on each web. The assembled stack is cut off into convenient lengths which are then packaged in wrappers or paperboard boxes for use by the consumer.

ln interfolding apparatus and methods employed heretofore, difficulties were encountered in assembling the webs in the stack at the requisite high speed while at the same time avoiding wrinkles, creases or breakage of individual webs. In many types of interfolding machines, the various folding devices included boards, rods or other structural elements which formed welldefined line contacts, and the webs tended to wrinkle or crease as they moved over such elements. The wrinkling and creasing of the webs was of special moment in cases in which the webs were folded too quickly or were otherwise subjected to unnecessary handling, such as in machines where a given web was folded and then reopened for insertion of an edge portion of a succeeding web, or where an edge portion was turned sharply over or under itself in a so-called reverse" fold, for example. These problems represented a serious deficiency in machines used heretofore and often resulted in a substantial wastage of material and an inferior product.

Still another difficulty encountered in several previous machines arose because of the increasing height of the stack of webs as it moved along its feed path toward the outfeed end of the machine. As the stack approached the outfeed end, it frequently exhibited a tendency to bind, with the result that the overall efficiency of the machine was further impaired.

Additional difficulties exhibited by many prior interfolding machines resulted from the core assemblies used within each supply roll to facilitate the handling of the roll and its positioning on the machine. When a given roll exhausted its supply of tissue, for example, the spent core was manually removed from the machine, and the handling assembly within the core was detached in a more or less haphazard manner. The time required to remove the core, detach the handling assembly, insert the assembly in a fresh roll and position the fresh roll on the machine was excessive and resulted in unnecessary delays in the tissue folding operation.

SUMMARY OF INVENTION The present invention is useful wherever a stack or package of folded webs is desired. The invention overcomes the foregoing and other disadvantages and achieves its primary object particularly in facial tissue manufacture by the provision of a new and improved machine and method for interfolding a succession of webs.

More specifically, an object of this invention is to provide such interfolding apparatus and method which avoids the unnecessary formation of creases and wrinkles in the webs being folded.

Another object of the invention is to provide an apparatus and method of the character indicated in which the handling of the various web supply rolls and cores therefor is greatly facilitated.

An additional object of the invention is to provide a web interfolding machine which is capable of high speed operation but which may be rapidly brought to rest without substantial breakage or slackness of the webs.

A further object of this invention is to provide an interfolding machine which is adjustable in accordance with the varying heights of the stack of webs being folded.

Still another object of the invention is to provide an interfolding apparatus and method in which the core assemblies for the individual supply rolls are readily inserted in and removed from the roll cores.

A still further object of the invention is to provide a high speed web folding machine utilizing comparatively simple mechanical components which is economical to manufacture and thoroughly reliable in operation.

In one illustrative embodiment of the invention, there is provided a machine and method for interfolding a group of webs from a plurality of supply rolls of tissue or other sheet material. The webs are led in a unique manner to a series of folding devices, one for each web, which are disposed in spaced relationship with each other along a feed path. Successive folding devices have alternate left and right pairs of curved folding shoulders, and the shoulders of each device are arranged to form a trough in the corresponding web and to initiate the gradual closing of the trough. As the web moves past succeeding folding devices, the gradual closing of the trough is continued, but the trough is not fully closed until after an edge portion of the next web is located in the trough. The thus interfolded webs are advanced in a stack by a belt type conveyor, and the stack is cut to appropriate lengths at the outfeed end of the conveyor for packaging and delivery to the purchaser.

In accordance with one feature of several embodiments of the invention, each folding device (except the first device) is provided with a guide member which receives the web from the immediately preceding folding device and continues the gradual closing of the trough while positively preventing the completion of the fold. The trough is not closed until after an edge portion of the succeeding web has been laid down and the web has moved past a following folding device. The arrangement is such that the trough in each web is closed in an extremely gradual manner by three successive folding devices, and there is no necessity for folding and then reopening the edge portions of the web in order to insert a succeeding edge portion therebetween.

In accordance with another feature of the invention, in certain preferred embodiments, the curved folding shoulders on each folding device are of comparatively large radii and are arranged such that the webs seek their own position as they approach the continuously moving stack. During the interfolding operation sharp reverse folds and other abrupt changes in direction of the edge portions of the webs are avoided, and the incidence of unwanted creases or wrinkles in the assembled webs is greatly reduced.

In accordance with a further feature of certain advantageous embodiments of the invention, as each web is received by its folding device a shallow trough is formed in the web, and the trough is then turned inside out and the web direction changed so that it is substantially parallel to the path of the stack. The inside out trough passes smoothly and easily over the curved folding shoulders of the folding device and is closed by the second succeeding folding device to fully interfold the web into the stack.

In accordance with an additional feature of several embodiments of the invention, the curved shoulders of each folding device are spaced apart to define a generally slot-shaped opening therebetween. The fold is initiated in the portion of the web which passes along the slot-shaped opening, with the result that an extremely smooth and uniform fold is produced.

In accordance with still another feature of the invention, in several good arrangements, the supply rolls for the webs are located along only a single side of the web feed path but include novel infeed mechanisms which direct the successive webs to the conveyor from opposite sides of the path. With this arrangement, the handling of the supply rolls and the spent cores therefor is greatly facilitated.

In accordance with a further feature of certain advantageous embodiments of the invention, there is provided a cutter mechanism for each supply roll which divides the sheet material from the roll into a plurality of webs. The number of supply rolls is substantially less than the number of webs, and the time needed for monitoring and replacing the rolls is accordingly reduced.

In accordance with a still further feature of the inven tion, in some embodiments, the machine includes a mechanism for depositing the spent cores for the supply rolls on a conveyor which transports the cores to a central location adjacent one end of the machine. A back-up roll adjacent each supply roll is then moved into an operative position on the machine. As a result, the time required for replacing a given roll is substantially reduced.

In accordance with another feature of the invention,

in certain arrangements, the cores for the supply rolls are provided with core assemblies which may be readily expanded and contracted from one end of the core. The assemblies are readily inserted in and withdrawn from the cores in a rapid and straightforward manner.

In accordance with still another feature of the invention, in some embodiments, the assembled webs are ad vanced along the stack by a conveyor having an outfeed portion which is adjustable to conform to the height of the stack. To avoid unnecessary strain on the webs, each of the supply rolls is provided with an independent drive mechanism which is synchronized with the stack conveyor, thus providing an extremely smooth and uniform flow of material from the supply rolls to the outfeed end of the machine. The cutter mechanism also includes an independent drive for the material. In addition to its other advantages, the use of a plurality of independent drive mechanisms facilitates the rapid and smooth stopping of the material when the machine is shut down without substantial breakage or slackness of the webs.

The present invention, as well as further objects and features thereof, will be understood more clearly and fully from the following description of certain preferred embodiments, when read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary perspective view of a plurality of tissue webs being interfolded into a stack of webs in accordance with one illustrative embodiment of the invention.

FIG. 2 is a sectional view of the interfolded webs taken along the line 2-2 in FIG. 1.

FIG. 3 is a perspective view of portions of two successive folding devices which are representative of the devices used to form the folds shown in FIGS. 1 and 2.

FIG. 4 is a top plan view of one of the folding devices illustrated in FIG. 3.

FIG. 5 is a side elevational view of the folding device shown in FIG. 4.

FIG. 6 is a rear view of the folding device as seen from the left of FIG. 5.

FIG. 7 is a front view of the folding device as seen from the right of FIG. 5.

FIGS. 8, 9 and 10 are vertical sectional views taken along the corresponding lines 8-8, 9-9 and 10-10 in FIG. 5, with portions of the structure omitted for purposes of clarity.

FIG. 11 is a front view of the device as seen from the line 11-11 in FIG. 5, with portions of the structure omitted for purposes of clarity.

FIG. 12 is a sectional view taken along the line 12-12 in FIG. 5.

FIG. 13 is a side elevational view similar to FIG. 5 but showing additional structure.

FIG. 14 is a fragmentary top plan view of a series of folding devices and their associated webs in position on the machine.

FIG. 15 is a fragmentary side elevational view of the portion of the machine shown in FIG. 14.

FIGS. 16 and 17 are vertical sectional views taken along the respective lines 16-16 and 17-17 in FIG. 15 to illustrate the folding of one of the webs by a righthand folding device, with portions of the structure omitted for purposes of clarity.

FIGS. 18 and 19 are vertical sectional views taken along the respective lines 18-18 and 19-19 in FIG. 5 to illustrate the folding of one of the webs by a lefthand folding device, with portions of the structure omitted for purposes of clarity.

FIGS. 20 and 21 are vertical sectional views of the webs taken along the respective lines 20-20 in FIG. 15 to illustrate the webs at succeeding points along the path of the stack.

FIG. 22 is a fragmentary top plan view of a folding bar and associated parts for changing the direction of movement of a web preparatory to its insertion into the stack.

FIG. 23 is a vertical sectional view taken along the line 23-23 of FIG. 22.

FIGS. 24 and 25 are sectional views taken along the respective lines 24-24 and 25-25 in FIG. 23.

FIG. 26 is an end elevational view of a machine for interfolding a series of webs, with certain parts omitted and others shown in section.

FIG. 27 is a vertical sectional view, partly broken away, of a tissue supply roll for the machine having an expandable core assembly, taken along the line 27-27 in FIG. 26.

FIG. 23 is a top plan view of a portion of the machine as seen from the line 28-28 in FIG. 26, with some of the backup rolls omitted for convenience of illustration.

FIG. 29 is an enlarged fragmentary sectional view taken along the line 29-29 of FIG. 28.

FIG. 30 is an enlarged end elevational view similar to a portion of FIG. 26 but showing certain of the parts in different positions.

FIG. 31 is a side elevational view of the machine frame and associated components adjacent the outfeed portion of the machine.

FIG. 32 is a side elevational view of the machine frame and associated components adjacent the infeed portion of the machine.

FIGS. 33, 34 and 35 are schematic illustrations of the varying positions of the conveyor for the stack of webs.

FIG. 36 is a perspective view of two folding devices and cooperating components in accordance with another illustrative embodiment of the invention, together with a schematic representation showing the location of the tissue webs being interfolded.

FIG. 37 is a vertical sectional view of the webs taken along the line 37-37 in FIG. 36.

FIG. 33 is a fragmentary side elevational view of a folding device in accordance with a further illustrative embodiment of the invention, together with a schematic representation showing the location of the tissue webs being interfolded.

FIG. 39 is a vertical sectional view of the webs taken along the line 39-39 of FIG. 38.

FIG. I0 is a fragmentary vertical sectional view of an alternative conveyor and adjustment mechanism useful in connection with the invention.

FIG. 41 is a fragmentary sectional view taken along the line 4l-4I in FIG. 40.

DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS As will be understood, the process of producing facial tissues includes the drawing together and folding into a continuous stack many tissue webs from a long line of tissue supply rolls. The stack is cut off into convenient lengths which are then packaged in wrappers or paperboard boxes which go to the consumer.

In the version of the present invention illustrated in the drawings, the supply rolls are supported about fixed axes, and the webs are fed through a series of folding devices onto a stack which is moved relative to the supply rolls. In other versions of the invention, however, the supply rolls may be supported about axes which travel in a closed path countercurrent to the direction of movement of the stack, so that the relative movement of the webs and the supply rolls is the resultant of the combined movement. These latter versions are substantially shorter than the illustrated version and are of particular utility in cases where space is at a premium. For a more detailed description of the countercurrent movement of the supply rolls and the webs, reference may be had to U.S. Pat. Nos. 3,285,599 and 3,472,504 identified above.

In order to facilitate the description of the illustrated embodiments of the invention, there will first be given a description of the construction and mode of opera tion of the various folding devices for interfolding the webs into the stack. There will then be described the construction and operation of the overall interfolding machine, including the supply rolls and their core assemblies, the roll drive mechanisms, the tissue cutting assemblies and the conveyor for the stack. That description will be followed by a description of various alternative folding devices that may be employed on the machine.

THE WEBS AND THEIR FOLDING DEVICES Referring to FIGS. I and 2 of the drawings, there is shown a plurality of facial tissue webs 50 being interfolded and assembled into a longitudinally extending stack SI which defines a feed path. In the drawings, the reference numerals for the webs 50 are followed by an alphabetical suffix in order to differentiate therebetween. Thus, FIG. I is illustrative of five successive webs 50a, 50b, 50c, 50d and 50e as they are interfolded into the stack 51. During the folding operation, a median or V" fold 52 is formed in each web along its longitudinal center line, and this fold divides the web into a pair of edge portions, such as the: edge portions 50a] and 50112 of the web 50a. The edge portions of the various webs extend in transverse cross-section continuously from the fold 52 to the opposite edges of the web. The lowermost edge portion of each web is interfolded between the edge portions of the immediately preceding web, with the result that after the stack has been cut to box-size lengths and packaged, the removal of a given tissue from the box causes an edge portion of the tissue therebeneath to pop up" into removal position.

The webs 50 are introduced into the stack 51 from opposite sides of the feed path. The web 50a is folded with the opening between its edge portions to the right, when viewed in the direction of movement of the stack, thus forming a right-hand fold. The successive webs are folded alternately to provide a left-hand fold in the web 5011, a right-hand fold in the web 50c, a left'hand fold in the web 50d, a right-hand fold in the web 50c, and

so on.

As each of the tissue webs 50 approaches the stack 51, the web is traveling in a direction which meets the path of the stack at approximately a right angle. A shallow trough 53 is formed in the web, and the web direction is then changed so that it is substantially parallel to the stack. As the web changes direction, the trough 53 is turned inside out to produce a longitudinally extending trough 54, the inversion of the web being assisted by the natural stretchability of the tissue. The trough 54 is gradually closed by moving the edge portions of the web along gradually curving paths to initiate the formation of the fold. The fold for each web is not completed, however, until after the web passes the point along the stack at which the trough 54 is formed in the second succeeding web. With respect to the web 50a, for example, the edge portions 50a1 and 50:12 are positively maintained in spaced-apart relationship with each other to prevent the completion of the fold as the first succeeding web 50b reaches the stack and its lowermost edge portion 50b1 is inserted between the open edge portions of the web 50a. The edge portions Sllal and 50a2 continue in spaced relationship as the web 50a moves past the point at which the trough 54 is formed in the second succeeding web 50c. The edge portions 50a1 and 50112 are then closed, and the webs proceed along the path of the stack in interfolded relationship with each other.

The interfolding of the various webs 50 is performed through the use of a series of folding devices 55 which are mounted in spaced relationship with each other along the feed path defined by the stack 51. One of these folding devices is provided for each of the webs to be interfolded, and alternate devices are mirror images of each other to initiate the formation of righthand and then left-hand folds. In FIG. 3, for example, there are shown a right-hand folding device 55c for the web 500 and a left-hand folding device 55d for the web 50d. The devices 55c and 55d are each provided with a pair of'surfaces 56 and 57 which have curved folding shoulders 58 and 59. As each of the webs 50c and 50d approaches the corresponding device 55c or 55d, it passes over a guide roller 60 immediately adjacent the infeed side of the folding device and is then drawn along the device with its upper and lower edge portions in respective contact with the folding shoulders 58 and 59. The shoulders direct the edge portions along gradually curving paths to initiate the formation of the fold.

Each of the folding devices 55 is of one-piece construction and illustratively may be cast from aluminum or other material or may be bent from a single flat sheet of rectangular configuration. FIGS. 4-13 depict a righthand folding device, it being understood that the lefthand folding devices are of similar construction but are reversed as shown by the device 55d in FIG. 3. The folding shoulders 58 and 59 of all of the devices are spaced apart to define a generally slot-shaped opening 62 therebetween. The opening 62 extends in a direction substantially parallel to the feed path of the stack of webs but gradually slopes downwardly toward the path such that the inner longitudinal edges 63 and 64 (FIG. of the surfaces 56 and 57 form small acute angles 0 amd 0 with the stack. As best shown in FIG. 4, the edge 64 of the surface 57 lies in a vertical plane which is parallel to the direction of movement of the stack.

The rearward portion of each of the folding devices 55 is provided with a triangular infeed surface 65. Two additional triangular surfaces 66 and 67 are interposed between the respective surfaces 56 and 57 and the infeed surfaces 65. The intersections between the surfaces 56 and 66 and between the surfaces 57 and 67 are of relatively large radii to form the respective folding shoulders 58 and 59. The common intersection of all of the surfaces includes a keyhole-shaped opening 68 to eliminate the slight hump that would otherwise be present. The opening 68 is contiguous with the infeed end of the slot 62, and the major portion of the opening is disposed in the surface 65.

A guide member 70 (FIG. 13) is bolted or otherwise rigidly secured to the lowermost surface 67 of each of the folding devices 55. The guide member 70 includes a curved shoulder 71 which is disposed immediately beneath the folding shoulder 59. The shoulder 71 slopes downwardly toward the stack of webs therebeneath.

As best shown in FIG. 14, the infeed rollers 60 for alternate ones of the folding devices 55 are positioned on opposite sides of the feed path defined by the stack of webs 51. Thus, the rollers 60 for the right-hand folding devices 55a and 550 are located on one side of the feed path, and the rollers for the left-hand folding devices 55b and 55d are located adjacent the opposite side of the feed path. The folding devices 55 are staggered with respect to the feed path, with the folding shoulders 58 and 59 (FIG. 13) of successive devices arranged in alternate right and left pairs. The additional shoulders 71 on the devices 55 likewise alternate, such that the shoulders 71 on successive devices extend over the feed path from opposite sides.

Pivotally mounted adjacent each of the rollers 60 is a guide bar 74. The bar 74 meets the direction of movement of the stack of webs at an acute angle which illustratively is of the order of forty-three degrees but which may be quickly and easily adjusted to provide a smooth and uniform flow of tissue around the bar. The lower end of the bar 74 is pivotally supported in a recess 76 (FIGS. 22-25) in a mounting block 77. A forwardly extending arm 78 is disposed within the recess 76 and is affixed at one end to the lower end of the bar. A bolt 79 at the opposite end of the arm 78 extends through oblong slots 80 in the block 77. To adjust the angle between the bar 74 and the direction of movement of the stack of webs, the bolt 79 is loosened to permit pivotal movement of the bar relative to the block.

The mounting block 77 for each of the guide bars 74 is welded or otherwise secured to a slidable plate 82. As best shown in FIG. 25, the plate 82 is interposed between a pair of fixed guides 83 which are respectively disposed along the longitudinal edges of the plate to permit movement of the plate and the attached guide bar in a direction parallel to the stack of webs. A knurled knob 84 adjacent the forward end of the plate 82 controls a threaded post 85 which extends through an oblong aperture 86 in the plate 82 into a fixed plate 87 mounted on the frame of the machine. Upon the loosening of the knob 84, the plate 82 and its attached guide bar 74 may be moved in a forward or rearward direction along the path of the stack to permit an additional adjustment in the position of the bar, and hence the position of the web 50 on the roller 60.

The successive webs 50a, 50b, 50c and 50d( FIGS. 14 and 15) approach the corresponding folding devices 55a, 55b, 55c and 55d from above and from opposite sides of the feed path. Each web passes around the angularly extending guide bar 74 to change the direction of movement of the web from a substantially vertical direction to a rearward direction. The web then moves over the roller 60 and enters its folding device with the web in contact with the triangular infeed surface 65. As the web proceeds along the folding device, the upper and lower longitudinal edge portions are drawn along the triangular surfaces 66 and 67, respectively.

The portion of the web 50 in contact with the infeed surface 65 is moving in a direction substantially transverse to the direction of movement of the stack of webs. The portions of the web in contact with the surfaces 66 and 67, on the other hand, are disposed in planes which are substantially parallel to the direction of movement of the stack. As a result, during its movement over the surface 65 the web becomes bowed to form the shallow trough 53.

The web 50 moves from the infeed surface 65 into contact with the folding shoulders 58 and 59. As the web contacts these shoulders, it changes direction approximately ninety degrees so that it is travelling substantially parallel to the path of the stack. Simultaneously, the shoulders 50 and 59 act on the web to turn the trough 53 inside out, thus forming the trough 54. Upon continued movement of the web along the folding device, the edge portions of the web ride along the shoulders and are gradually urged toward one another to begin the closing of the trough along the fold line.

At the time the web 50a, for example, nears the outfeed end of its folding device 55a and reaches the position shown in FIG. 17, the formation of the trough 541 has been initiated, and the edge portion 50a1 is disposed above the edge portion 50:12. However, the edge portions 50111 and 50a2 are maintained in spaced-apart relationship with each other at this point along the path of travel to prevent the completion of the fold.

As the web 50a continues its movement along the feed path and reaches the immediately succeeding folding device 55b, the folding shoulder 71 on the guide member 70 is located within the trough 54. As best shown in FIG. 18, the guide member 70 is interposed between the edge portions 5001 and 50a2 to affirmatively prevent the completion of the fold in the web 5001. The succeeding web 50b moves around the corresponding bar 74 and the roller 60, and the web enters the folding device 55b with the web in contact with the infeed surface 65. In the position shown in FIG. 19, the edge portions Sb1 and 50b2 of the web 501) are in facing contact with the surfaces 56 and 57, respectively, on the folding device 55b. In this position the edge portion 50all of the web 500 rests on the upper surface of the edge portion 50b2 and is interposed between the portions 50b1 and 50b2.

The trough 54 in the web 50a remains open as the web moves from the folding device 55b to 550. The web 50a passes beneath the device 55c, and by the time it reaches the position shown in FIG. 20 it is fully interfolded into the stack.

In a similar manner, the fold in the succeeding web 50b is initiated as the web passes along the folding shoulders 50 and 59 of the folding device 55b. As the web 5012 continues its movement, the completion of the fold is affirmatively prevented by the shoulder 71 on the folding device 550. Upon the movement of the web 50b from the position shown in FIG. 20 to that shown in FIG. 21, the web leaves the folding device 55d and reaches its fully interfolded position.

Each successive web is interfolded into the stack in similar fashion as it moves along three succeeding folding devices. The folding devices are positioned in close proximity with one another along the path of the stack. In addition to its other advantages, the use of three folding devices tocomplete the interfolding of a given web insures that the edge portions of the web move along gradually curving paths without abrupt changes in direction, with the result that extremely smooth folds are produced with a minimum of wrinkles and creases in the webs.

THE MACHINE SUPPLY ROLLS AND CORE ASSEMBLIES Referring to FIG. 26, the tissue or other sheet mateslightly rial from which the webs 50 are formed is fed to the various folding devices 55 from a series of supply rolls 90. One of the rolls is provided for each group of four folding devices 55, and the material from each roll is slit, in a manner to be more fully described hereinafter, into four separate webs which are led to the individual folding devices.

Each of the supply rolls 90 is supported between a pair of horizontal beams 92 and 93 (FIG. 28). The beams 92 and 93 are mounted intermediate their ends on upright columns 94 and angularly disposed braces 95. The braces 95 extend from the lower ends of the columns 9 1 to a group of posts 96 which form portions of the frame 97 of the machine.

A back-up roll 98 is disposed immediately adjacent the supply roll 90 in position to be moved to an operative location on the machinewhen the material on the supply roll is exhausted. The back-up roll 98 is carried by a cart 100 having two horizontal beams 10] and 102 which are arranged to mate with the corresponding beams 92 and 93 on the machine. The beams 101 and 102 are each provided with a tongue 103 which abuts the adjacent beam 92 or 93 to locate the cart 100 in position.

The supply rolls 90 and the back-up rolls 98 include the usual paperboard cores 104. Removably mounted within each core is an expandable core assembly or chuck 105. As best shown in FIG. 27, each of the chucks 105 includes a central shaft 106 surrounded by a sleeve 107 which is rotatable with respect to the shaft. The sleeve 107 is provided with bearings 108 which serve to maintain the sleeve in spaced relationship with the shaft 106.

Affixed to the opposite ends of the sleeve 107 are generally disk-shaped wheels 110 and 111. Inflatable tubes 112 and 113 of rubber or other resilient material are respectively mounted on the wheels 110 and 111. The tube 112 communicates with a conventional air inlet 115 through a four-way connection 116, and the tube 113 similarly communicates with an air inlet 117 through a four-way connection 118. The inlets 115 and 117 are disposed at opposite ends of the chuck 105 in locations which are readily accessible to a suitable'air hose (not shown). The connections 116 and 118 are provided with normally closed vent valves 120 and 121, respectively. These valves are located immediately adjacent the corresponding inlet 115 and 117. The connections 116 and 110 communicate with each other through a conduit 122 which is located within the rotatable sleeve 107.

The chuck 105 is manually inserted into one end of the core 104 in a deflated condition and may be controlled entirely from that end of the core. When the chuck 105 is in position, air is supplied to the tubes 112 and 113 through one of the inlets 115 or 117. Upon the admission of air into the inlet 115, for example, the air flows through the connection 116 to the tube 112 and also along the conduit 122 and the connection 118 to the tube 113. As the tubes 112 and 113 are inflated, they bear against the inner cylindrical surface of the core 104 to rigidly hold the tubes, the wheels 110 and 1.11, and the sleeve 107 within the core and to maintain the shaft 106 in coaxial relationship therewith. The shaft 106 is free to rotate relative to the core 104 and the surrounding roll, however, to facilitate the feeding of the material on the roll to the machine. 

1. In apparatus for longitudinally interfolding a plurality of webs and for advancing the interfolded webs in a continuously moving stack along a feed path, in combination: a plurality of folding devices mounted in spaced relationship with each other along the feed path, each of said folding devices having an infeed surface and an outfeed surface extending from and continuous with said infeed surface in the direction of movement of the stack along the feed path, said outfeed surface including a pair of gradually curved diverging folding shoulders, at least one of said folding shoulders extending at an angle from a portion of the infeed surface adjacent the feed path obliquely across at least a portion of the feed path, and outfeed surface portions extending laterally from said folding shoulders defining a concave surface, as viewed from the preceding folding device, between the folding shoulders for concavely folding the portion of a web drawn therebetween, said folding devices being disposed along the feed path so that the concave outfeed surface portion of each folding device can receive the portion of the folded web from the preceding folding device to be interfolded with the web supplied to said folding device; means associated with each of said folding devices for guiding the portion of the folded web from the preceding folding device to be interfolded with the web supplied to said folding device into the concave outfeed surface portion of said folding device so that the folding shoulder which extends across the feed path is interposed between said portion of the folded web to be interfolded and the remainder of said folded web opposiTe said portion; means for supplying a web to each of the folding devices; and means for drawing the web supplied to each of the folding devices over the infeed and outfeed surfaces of said folding device and into the stack so that said web is folded concavely around the portion of the folded web from the preceding folding device guided into the concave outfeed surface portion of said folding device as said web passes the outfeed surface of said folding device and so that a portion of said web on the side of the fold adjacent the interposed folding shoulder is gradually interposed between the folded surfaces of the web from the preceding folding device by said interposed folding shoulder to interfold said web and the web from the preceding folding device, and a portion of the web on the other side of the fold is positioned by the other folding shoulder for guiding into the concave outfeed surface portion of the succeeding folding device.
 2. The apparatus defined in claim 1 wherein the infeed surface of each folding device is substantially perpendicular to the feed path.
 3. The apparatus defined in claim 2 wherein the infeed surface of each folding device is substantially triangular.
 4. The apparatus defined in claim 44 wherein the folding shoulders of each folding device extend from the region of a corner of the triangular infeed surface of said folding device.
 5. The apparatus defined in claim 1 wherein said means for supplying comprises: a plurlaity of supply rolls of sheet meaterial; means for longitudinally slitting said sheet material from said supply rolls to produce a plurality of webs; and means for respectively directing said webs to said folding devices.
 6. The apparatus defined in claim 1 wherein said means for drawing comprises conveyor means for supporting the stack of interfolded webs and for advancing said stack along said feed path.
 7. The apparatus defined in claim 6 further comprising means for adjusting the position of said conveyor relative to said folding devices in accordance with the number and thickness of webs in said stack.
 8. The apparatus defined in claim 1 wherein the outfeed surface of each of said folding devices further includes an extension of the folding shoulder which is not interposed between portions of the folded web from the preceding folding device for longitudinally creasing the portion of the web supplied to said folding device adjacent said folding shoulder extension in the opposite direction from said concave fold and wherein said apparatus further includes means associated with each of said folding devices and disposed in spaced relationship therewith for defining an opening therebetween for receiving the portion of the web extension from the crease formed by said folding shoulder extension in the direction away frm said concave fold and for further positioning the received portion of the web for guiding into the concave outfeed surface portion of the succeeding folding device.
 9. In apparatus for longitudinally interfolding a plurality of webs and for advancing the interfolded webs in a continuously moving stack along a feed path, in combination: a plurality of folding devices mounted in spaced relationship with each other on alternate sides of the feed path, each of said folding devices having an infeed surface and an outfeed surface extending from and continuous with said infeed surface in the direction of movement of the stack along the feed path, said outfeed surface including a pair of gradually curved diverging folding shoulders extending from a portion of the infeed surface adjacent the feed path obliquely across at least a portion of the feed path, and outfeed surface portions extending laterally from said folding shoulders, said outfeed surface portions and folding shoulders respectively defining convex surfaces as viewed from the preceding folding device, outside the folding shoulders and a concave surface between the folding shoulders, said outfeed surface being substantiaLly convex adjacent the infeed surface and becoming substantially concave as the folding shoulders diverge toward the outfeed end of the folding device, for forming a convex longitudinal trough in a web drawn over the outfeed surface of the folding device and for gradually inverting said trough as the web is drawn over the folding shoulders and into the concave outfeed surface portion between the folding shoulders, the outfeed surface portions defining the bottom of the concave outfeed surface being sufficiently close together to concavely crease the portion of the web drawn therebetween; means associated with each of said folding devices for preventing the inverted trough in the web from the preceding folding device from closing and for guiding one edge of the web from the preceding folding device into the concave outfeed portion of said folding device so that one of the folding shoulders of said folding device projects at least partially into said inverted trough for interfolding said edge with the web supplied to said folding device; means for supplying a web to each of the folding devices; and conveyor means for drawing the web supplied to each of the folding devices over the infeed and outfeed surfaces of said folding device and into the stack so that said web is creased concavely around the edge of the web from the preceding folding device guided into the concave outfeed surface portion of said folding device as said web passes the outfeed surface of said folding device, and so that at least a portion of the web on the side of said crease adjacent the folding shoulder projecting into the inverted trough in the web from the preceding folding device is gradually introduced into said inverted trough by said projecting folding shoulder and is thereby interfolded with the web from said preceding folding device.
 10. The apparatus defined in claim 9 wherein the infeed surface of each folding device is substantially perpendicular to the feed path.
 11. The apparatus defined in claim 10 wherein the infeed surface of each folding device is substantially triangular.
 12. The apparatus defined in claim 11 wherein the folding shoulders of each folding device extend from the region of a corner of the triangular infeed surface of said folding device.
 13. The apparatus defined in claim 12 wherein the outfeed surface portions of each of said folding devices defining said convex surface extend from the two sides of the triangular infeed surface adjacent the region of said corner of the triangular infeed surface of said folding device.
 14. The apparatus defined in claim 13 wherein the periphery of the triangular infeed surface of each of said folding devices is indented in the region of said corner of said triangular surface to define a keyhole-shaped aperature in said infeed surface between said folding shoulders for initiating formation of the inverted trough in the web drawn over said folding device.
 15. The apparatus defined in claim 9 wherein said means for supplying comprises: a plurality of supply rolls of sheet material; means for longitudinally slitting said sheet material from said supply rolls to produce a plurality of webs; and means for respectively directing said webs to said folding devices.
 16. The method of longitudinally interfolding a plurality of webs to produce a stack of interfolded webs moving continuously along a feed path comprising the steps of: respectively guiding said webs to a plurality of locations on alternate sides of said feed path; forming a convex longitudinal trough in each of said webs as it is guided to said feed path, said trough being convex as viewed from the preceding web approaching the feed path and having a longitudinal axis which meets the feed path at an acute angle; gradually inverting a medial portion of the convex trough in each of said webs as said web merges with the stack of webs to form a concave longitudinal trough in said web; guiding a first edge portion of the cOncave trough in each of said webs into the concave trough of the preceding web to interfold said web with the preceding web; guiding the remaining edge portion of the concave trough in each of said webs into the concave trough of the succeeding web to permit the succeeding web to be interfolded with said web; and closing the concave trough in each of said webs following completion of the two immediately preceding steps for said web.
 17. The method of longitudinally interfolding a plurality of webs to produce a stack of interfolded webs moving continuously along a feed path comprising the steps of: respectively guiding said webs to a plurality of locations along one side of said feed path; forming a convex longitudinal trough in each of said webs as it is guided to said feed path, said trough being convexly bowed out toward one lateral side of the feed path as viewed from the preceding web approaching the feed path and having a longitudinal axis which meets the feed path at an acute angle; gradually inverting a portion of the convex trough in each of said webs as said web merges with the stack of webs to form a concavely bowed trough facing said one lateral side of the feed path in a portion of said web while maintaining a parallel convex trough in the lateral portion of said web adjacent the concave trough; guiding an edge portion of the concave trough in each of said webs into the convex trough of the preceding web to interfold said web with the preceding web; guiding an edge portion of the convex trough in each of said webs into the concave trough of the succeeding web to permit the succeeding web to be interfolded with said web; and closing the concave and convex troughs in each of said webs following completion of the two immediately preceding steps for said web. 